## andriod09 3 years ago Quadratic Equation question How do i get from: $x=-11\pm \frac{121-60}{ 6 }$ to the next part?

1. andriod09

@jwheele1

2. jwheele1

ok

3. cos00155079

im working on those problems too im not that good but i would simplify 121-6/ then.. which is?

4. jwheele1

well first of all.....write out two different equations to eliminate that +-

5. andriod09

@cos00155079 you doing the Life of Fred series?

6. andriod09

you don't have to do that @jwheele1

7. jwheele1

i know you dont have to but its easier...its cool we wont do that then

8. cos00155079

the what? nooo...

9. jwheele1

121 - 60 = ?

10. andriod09

61

11. andriod09

10

12. andriod09

$1$ $-21$

13. cos00155079

why 60/6 if it was a 61?

14. andriod09

ik

15. jwheele1

alright lets see now...

16. andriod09

the equation is: $x=-11\pm \frac{ \sqrt{121-60} }{ 6 }$

17. jwheele1

oh lawd....lol

18. jwheele1

sq rt of 121 = 11

19. jwheele1

whats with teh line over the 0?

20. andriod09

its just how it is. not my doing.

21. jwheele1

well...it means that its a repeating number but its usually only after a decimal point...weird.

22. jwheele1

I have no idea what to do with the 60 and the line over it.

23. andriod09

the original equation is: $3x^{2}+11x+5=0$

24. jwheele1

any specific way she is wanting you to go about that?

25. andriod09

its a messup about square roots.

26. jwheele1

or can we solve for x any old way?

27. andriod09

yea, using $ax^{2}+bx+c=0$ and the $x=-b\pm\frac{ \sqrt{b^{2}-4ac} }{ 2a }$

28. jwheele1

29. jwheele1

ok so 3x^2 + 11x +5 = 0 ax^2 + bx +c

30. jwheele1

a = 3 b = 11 c = 5

31. jwheele1

$-11\pm \frac{ \sqrt{11^{2}-4(3*5c)} }{ 2(3) }$

32. jwheele1

does that look right?

33. jwheele1

ignore the c next to the 5, lol |dw:1348620564257:dw|

34. jwheele1

|dw:1348620625370:dw|

35. jwheele1

i see where we screwed up now in the beginning

36. jwheele1

|dw:1348620687638:dw|

37. jwheele1

NOW......what has your teacher said to do with this?

38. jwheele1

because you can find common denominaters and put it all over one bar or you can leave it the way it is.

39. andriod09

I teach my self. I am homeschooled, i use the LoF series.

40. jwheele1

oh, cool

41. jwheele1

well....you could work it out to this way if you wanted to.... |dw:1348620830185:dw|

42. andriod09

the last answer i got was $x_{1}$ and $x_{2}$

43. jwheele1

OH yeah...i forgot this was all part of an original equation....this one might be too complicated for the quad formula. have you tried grouping method?

44. jwheele1

i mean factoring

45. andriod09

and it was $x=\frac{-9\pm7} { 8 }$ I did the quadratic formula on all of these so far, its a quadratic formula page. they're supposed to use the quadratic formula

46. jwheele1

ok well then we must find exact values

47. jwheele1

the sq rt of 61 is 7.810249675906654

48. jwheele1

divided by 6 = 1.301708279317776

49. jwheele1

-11 + 1.301708279317776 = ? -11 - 1.301708279317776 = ?

50. andriod09

we need not find exact values, we need to find $x_1$ and $x_2$

51. jwheele1

x1 and x2 are exact values

52. jwheele1

it appears anyways...this one is ugly

53. jwheele1

x1 = -9.698291720682224, x2 = -12.30170827931778 lol

54. jwheele1

none of this seems right to me and its driving me nuts, lol

55. jwheele1

for sure you need to find the square root of 61

56. jwheele1

which is not what you have in your original problem at the top

57. jwheele1
58. jwheele1

59. jwheele1

60. andriod09

its these: $x_{1}=\frac{ -11+\sqrt{61} }{ 6 }$ and $x_{1}=\frac{ -11-\sqrt{61} }{ 6 }$

61. jwheele1

thats what i would put....what you just put

62. andriod09

this is what my brother says, who is in college.

63. jwheele1

i am also in college. I woudl also stop there...I thought it was weird that were were trying to find the actual value for x1 and 2

64. andriod09

|dw:1348621589793:dw|

65. jwheele1

That is if you put it all under one common denominator which some teachers ask for...usually that is not what they want though

66. jwheele1

it means the same thing but most people show it liek yoru brother did

67. andriod09

w/e i have it and its done. thanks for any help!

68. jwheele1

yw